Comprehensive study of tropical theileriosis in Assiut province, Egypt, with reference to molecular findings in diseased cattle.

This study investigated the infection rate among clinically suspected cases, clinical aspects, pathological lesions and molecular characteristics of Theileria annulata in clinically suspected cases of cattle and buffaloes from Assiut Governorate, Upper Egypt. A total of 600 animals (500 cattle, 100 buffaloes) were examined using microscopy and PCR, revealing an infection rate of 32.2% in cattle and 20% in buffaloes. Clinical examination showed common signs of theileriosis, with infection rate significantly higher during the hot season. Postmortem and histopathological analysis confirmed the severity of the disease, demonstrating multi-organ lesions such as hepatomegaly, abomasal ulceration, lymphadenopathy, lymphoid depletion, hepatic necrosis, and fibrosis. PCR confirmed T. annulata DNA circulating in both cattle, and buffaloes, and in the primary vector, Hyalomma anatolicum ticks. Notably, T. annulata DNA was also detected in Hippobosca equina, suggesting a possible role for non-tick vectors in transmission. Phylogenetic analysis showed limited genetic diversity among the three isolates sequenced from this region. In conclusion: These findings confirm the endemicity and substantial pathological impact of T. annulata in Upper Egypt and provide molecular evidence suggesting alternative transmission routes beyond the primary tick vector.